1. Field of the Invention
The invention relates to pressurizing of a vessel from a selected supply gas at high pressure where the vessel is to be pressurized with precision predetermined value somewhat above atmospheric pressure.
2. Description of the Prior Art
In U.S. Pat. No. 3,021,865, issued Feb. 20, 1962 to Beckett, an external source of pressure provides necessary operating energy to a regulating mechanism which is quite complex mechanically and fails to incorporate safety relief devices for relieving excess pressures within the system. Moreover, the pressure regulator of Beckett fails to disclose a means of draining or relieving either condensed or entrained liquids. Such condensed or entrained liquids, by virtue of their weight alone, acting on the surface of a diaghragm, can render the system of Beckett inoperative. U.S. Pat. No. 3,047,010, issued July 31, 1962 to Rothfuss, and U.S. Pat. No. 3,454,044, issued July 8, 1969 to Mamzic disclose regulating devices which operate from and require an external source of power. Neither patent discloses a self-contained system utilizing the process fluid as the actuating medium. U.S. Pat. No. 1,306,746, issued Dec. 29, 1942 to Niesemann and U.S. Pat. No. 956,283, patented Apr. 26, 1910 by Cash, disclose regulators for maintaining a downstream set pressure of a fluid which is flowing, and neither arrangement would be useful for maintaining low pressures in a vessel, duct or chamber under static or non-flowing conditions.
Other related prior art arrangements are shown in the following patents:
______________________________________ 2,987,920 Du Bois June 13, 1961 3,411,429 Bassett Nov. 19, 1968 3,271,256 Bernard Mar. 20, 1973 ______________________________________